1.\" $NetBSD: errno.9,v 1.5 2010/03/22 18:58:33 joerg Exp $ 2.\" 3.\" Copyright (c) 2004 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Andrew Brown. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.Dd May 16, 2018 34.Dt ERRNO 9 35.Os 36.Sh NAME 37.Nm errno 38.Nd kernel internal error numbers 39.Sh SYNOPSIS 40.In sys/errno.h 41.Sh DESCRIPTION 42This section provides an overview of the error numbers used internally 43by the kernel and indicate neither success nor failure. 44These error numbers are not returned to userland code. 45.Sh DIAGNOSTICS 46Kernel functions that indicate success or failure by means of either 0 47or an 48.Xr errno 2 49value sometimes have a need to indicate that 50.Dq special 51handling is required at an upper layer or, in the case of 52.Xr ioctl 2 53processing, that 54.Dq nothing was wrong but the request was not handled . 55To handle these cases, some negative 56.Xr errno 2 57values are defined which are handled by the kernel before returning a 58different 59.Xr errno 2 60value to userland or simply zero. 61.Pp 62The following is a list of the defined names and their meanings as 63given in 64.In errno.h . 65.\"It is important to note that the value \-1 is 66.\".Em not 67.\"used, since it is commonly used to indicate generic failure and leaves 68.\"it up to the caller to determine the action to take. 69.Bl -hang -width Ds 70.It Er \-1 ERESTART Em "Restart syscall" . 71The system call should be restarted. 72This typically means that the machine dependent system call trap code 73will reposition the process's instruction pointer or program counter 74to re-execute the current system call with no other work required. 75.It Er \-2 EJUSTRETURN Em "Do not modify regs, just return" . 76No more work is required and the function should just return. 77.It Er \-3 ENOIOCTL Em "Ioctl not handled by this layer" . 78The 79.Xr ioctl 2 80was not handled and should be passed through to another layer. 81.It Er \-4 EMOUNTEXIT Em "Mountpoint released via vfs_start()" . 82Specific to 83.Xr mfs 8 . 84.El 85.Sh SEE ALSO 86.Xr errno 2 , 87.Xr ioctl 9 88.Sh HISTORY 89An 90.Nm 91manual page appeared in 92.At v6 . 93This 94.Nm 95manual page appeared in 96.Nx 3.0 . 97